Timing layshaft...

[Dirty Duc]

Totally make the beast with two backsed.

Woodruff keys are all beaten, and the woodruff slots for the pulleys are all buggered.

A mere 39k on an 06 S2R800.

What would have caused this? (I'll post pics later)

[Speeddog]

I'd say that the pulley nut was loose.

[Dirty Duc]

I did think it was looser than expected.  I thought that special nut was supposed to be semi-locking...

[Speeddog]

Well, it is a locknut, but the magic is limited.
If at some point it's not tight enough, it all goes haywire.

It's a small consolation, but I suspect you've discovered this before it gets to the point that the cam timing is so far off that it starts banging the pistons into the valves.
I've got some of the good parts left from of an engine that died that way.

[brad black]

we had a 996 that had movement at those pullies with the nut tight once.  it was one i had 1026'd and it came back a few months later not idling.  everything looked fine, but it wouldn't hold them.  i didn't fix it so i don't know what happened in the end.

are the lock clip and stepped washer ok?

[Dirty Duc]

I'm not sure what you mean by lock clip and stepped washer.

I pulled the alternator cover and all looked appropriate with bent washer for the gear-holding nut.

The washer between the pulleys looks like a big washer with a keyway, and the thin washer on the outside looks like a thin washer.

The keyways on the pulleys are beat a little (as to be expected).

It still ran, and actually ran halfway decent under acceleration over 5k RPM (I spent some time chasing this problem in fits and starts, and eventually it was time for a new set of belts), so I believe the valves to be ok.  No change in the vert shims from last time, anyway.

The really annoying part is the price of replacing layshaft and pulleys vs. the amount of work it will take.  I really didn't plan on rebuilding or replacing the engine this year.

[brad black]

oh, you're talking about the other end.  it's only 45nm, so not overly tight.

replace the key, tighten it all up, reset the cam timing and away you go.

[Dirty Duc]

[Dirty Duc]

I'd guess at 33lb/ft it was about right for tightness, then.

[brad black]

well, that's the end i was initially talking about.  remove both pullies, there's a clip on the shaft holding the inner pulley, possibly a stepped washer too.  depends on year.

that nut is 75nm.

[Dirty Duc]

Okay, the special nut was not at 75nm based on my arm torque meter when removing.  The clip is there, but no washer.

I'd guess the woodruff slot is nearly twice as big as it should be... that's the slot in the picture where the shiny bit is.

Have to split the cases to replace the shaft, it's a small case motor, just as easy to replace it based on time and energy.

Note to self, check torque on the pulleys when checking belts.

Although it was kind of difficult to remove the inner pulley from the shaft, so it may be that the lock clip is deformed in some difficult to measure way.

[Dirty Duc]

So, since it looks like the cases are coming apart...

Does a large case crank fit in a small case motor?  Can I bore it to 92mm?

I take it as given that I have to solve deck height problems and breathing issues...

[Speeddog]

Large case crank will fit, you'll need a 3-phase crank.

Rod journals are larger, so you'll need rods to suit.

Rods from 4V engines are the same length as small-case 2V rods, but small end is bigger diameter, so it'd need to be re-bushed.

Piston skirt clearance to crank cheeks at BDC may complicate the crank/rod combination choices.

I think the 'liner' skirt on the cylinder will fall off it you go out to 92mm.
I've got a motor in process that's 91mm pistons in (formerly) 88mm 750 barrels, and they're a bit thin.

A good primer on 'what-fits-what' here:
http://www.bikeboy.org/duccapacities.html

-------------------------------
Standard broken-record comment that's brought out in these situations......
It's generally cheaper to swap in a larger motor, versus rebuild/hop-up what you've got.
And cheaper still to fit a same-size complete used motor rather than rebuild.

But if you are doing most or all of the work yourself, that margin diminishes.
And if you just want to do it for the helluvit, and/or the cost isn't a big factor, then rock out!

[brad black]

i'd just put some new keys in it and do the nut up tight.  check and reset cam timing as required.

[Dirty Duc]

Speeddog, I have used Brad's site extensively.  I was looking for the couple of clues you provided.  I'm tracking on the broken record, I am just balking at the current market (reasonable looking big engine prices are currently asking for more than my bike would probably be worth).  The labor is all in-house, and I kind of like the idea of the stroker. 

Brad, it's probably my fault that the damage isn't obvious in the pictures, but the slots in the shaft are not shaped like slots anymore.  They are well and truly "wallered."  The slot in the shaft is half again as big as the slot in the pulley.  I have little confidence that I could find the proper timing locations, and even less confidence that a snug nut would keep them there.

I'm thinking piston availability is the current hurdle.  As I understand it, the 800 has the lowest wrist pin to face height of the 88mm pistons so custom rods might be in order with a long stroke crank.  Based on my research, compression height and transmission/layshaft clearances are more of a concern to me than skirt-crank clearance.  I'm probably wrong, but it will take cold hard facts to pry my delusions from my grasp.

The other question is what is the usual required kit for splitting the cases?